The invention lies within the technical field of jaw type clamping chucks, and it relates more especially to a chuck with six arms mounted on ball joints, compensated two by two.
There are known a certain number of workpiece clamping devices, for example chucks of the radial and axial clamping type but without compensated clamping, or again, chucks with one or more concentric or diameter-compensated jaws, of the radial clamping type, with or without axial clamping, with modifiable distribution between radial clamping and axial clamping, with compensation for said clamping types and distribution of the clamping force more or less equally for each jaw, as disclosed in document FR-A 2373 351.
More recently, modifications have been made to these systems by designing a clamping chuck permitting precise radial guiding of the jaw carriers in the body of the chuck, which also ensures their freedom to pivot axially with a view to optimum positioning of the jaws in contact with the workpiece for clamping. For this purpose, each jaw carrier is equipped with a member guided along a groove provided within the chuck, said guiding member being solely free to pivot axially in relation to the jaw carrier, as disclosed in document FR 2 720 670.
The three-jaw systems most commonly used do not, however, prevent the workpieces from being deformed under high speed machining conditions, which is why it was thought worthwhile to increase the number of points of contact between the chuck and the workpiece, to ensure better mating with its profile and avoid the risks of deformation. With this aim in mind, the Applicant has opted for a solution implementing six clamping jaws regularly distributed over the chuck, six arms mounted on ball joints and compensated two by two being provided.
The main object of the invention is thus a jaw type clamping chuck comprising several jaw carriers sliding in the body of the chuck through the action of a traction rod moving axially and comprising a mechanism converting this axial movement into a radial movement of the members for clamping of the workpiece effected by pivoting arms and a connection by truncated sphere and inclined plane, said clamping chuck comprising at least six jaw carrier arms which are actuated two by two by the same compensator, each compensator being articulated on a pulling member centered on the axis of the chuck and sliding axially in its main body through the action of the traction rod.
According to one particular feature of the invention, said compensator has two rectangular openings oriented along the radius of the chuck, the edges of the inner side of which form the ramp on which bears the plane face of the truncated sphere connected to the corresponding jaw carrier arm.
More precisely, the compensator hinges with the pulling member via a pin passing through a central hole in said compensator.
According to another particular feature of the invention, the pulling member is provided with at least three pairs of wings, with the wings extending on either side of the central portion of the compensator.